Auto rack rail road cars are used to transport automobiles. They may be used to transport finished automobiles from a factory to a distribution center. A long standing concern has been the frequency of damage claims arising from vandalism and theft of the rail car cargo. Unauthorized access to the rail cars may be achieved by prying open the rail car access doors. The access doors of rail cars described in the prior art typically have slots or other openings to accommodate bridge plates, support structures or other obstructions. These openings may weaken the structural integrity of the door, making the door less secure. The slots or openings may also provide an opening in which to insert a pry bar to force the door open. An example of a rail car having a door with slots is described in U.S. Pat. No. 4,944,234 issued to Hesch on Jul. 31, 1990, and entitled Rail Car End Assembly (the “Hesch Patent”). The Hesch Patent shows a rail car door with a number of slots to accommodate bridge plates. In addition to possibly weakening the door, these slots might be used to insert a pry or other object to gain unauthorized access to the rail car. The slots may also permit contaminants such as dirt and other foreign matter to enter the rail car, potentially damaging the rail car lading.
Auto rack rail road cars have ladders to permit rail yard personnel to ascend to or descend from the upper decks of the rail car. Typically, the ladders are located near to the doors. These ladders are preferably secured to the rail car body structure generally and are subject to vibration during operation of the rail car. The lower end of the ladder is typically secured to the first deck of the rail car, and the upper end of the ladder is typically secured to a support or brace member at the other end. The support, or brace, may be anchored to the top chord of one of the wall assemblies. In cars in which the door extends past the height of the top chord to obstruct access to the gable end, the positioning of the brace may tend to present design challenges. Due to mutual proximity, care is taken to avoid having the brace member interfere with the opening and closing of the door. As a result, the door may be configured to accommodate the ladder bracing. In U.S. Pat. No. 4,936,227, issued to Baker et al., on Jun. 26, 1990, and entitled End Door for Rail Car, interference with a brace member for the ladder is avoided by forming a notch in the outer edge of the door so that the door avoids collision with the brace. However this notch may tend to weaken the door and may also tend to permit dirt and other unwanted substances to enter the interior of the rail car. The notch may also provide an access point for vandals or thieves to pry the door away from the rail car.
U.S. Pat. No. 4,924,780, issued to Hart on May 15, 1990, and entitled Sliding End Panels for a Rail Car, shows a multi-panel door with a ladder attached to a panel of the door. The door employs a number of hinged panels, with each panel substantially supported and guided by a wheel on a narrow track. It has been observed that multi-panel, hinged doors may tend to require more maintenance, and more care in operation generally, than rigid panel radial arm doors. Further, each hinge, or opening, or crack may tend to provide a location at which vandals or thieves may seek access to the cars, or a point at which parts can be misaligned.
Single panel, or rigid assembly, doors may tend to be simpler to build and operate than multi-panel doors. An example of a rigid door is the radial arm door. Radial arm doors typically have a cross-section with an arcuate portion and a straight or linear portion tangent to the arcuate portion. The door may typically be supported by a pair of roller assemblies located along the lower edge of the arcuate portion and are constrained by the radial arm to follow a track of constant radius defining part of an arc of a circle. Since both rollers typically lie on the arc, the tangent portion of the door may tend to be cantilevered relative to the nearest roller. As a result, the roller assembly closest to the tangent portion may tend to support not only its share of the arcuate portion, but also most, or all of the weight of the tangent portion. This uneven weight distribution may cause the roller assembly nearest the tangent portion to wear prematurely. For example, in U.S. Pat. No. 3,995,563 of Blunden issued Dec. 7, 1976, two roller assemblies directly support the arcuate portion of the door. The tangent portion may therefore tend primarily to be supported by the roller closest to the meeting point of the tangent and arcuate portions. It would be advantageous to distribute the loading more evenly between the rollers.
In typical radial arm door installations, for example as shown by Blunden, the rollers are guided by an arcuate track having a flange. The track is mounted to the top surface of a first deck of the rail car. A roller housing connects the roller to the door. The housing has a J- or L-shaped extension in the nature of a finger, or hook, that overlaps the flange to tend to prevent the door from becoming separated radially from the track. Difficulties may arise if forces transverse to the track are applied to the door. For example, in the normal course of operation, the track may sag after years of operation under the weight of the door. If the track sags, the rollers may tend to work their way off the track surface. Alternatively, ice or some other obstruction may form or become lodged between the track and the roller. In either case, the door may be forced out of alignment with the track. If the extension becomes deformed then the door may not open and close properly. Similarly, if the track itself is not adequately supported then the track and door may begin to sag with extended use, causing similar difficulties. Even without obstructions or misuse of the door, the extension and track may wear out sooner than may be desirable if the track is constructed using relatively thin pieces of steel or other metal.
The roller and track arrangement described above may also leave a gap between the bottom edge of the door and the track. As noted above, such gaps may provide an access point for vandals, and may permit foreign matter such as dirt to gain access to the interior of the rail car. The presence of dirt and debris in particular may inhibit the roller from rotating if the dirt becomes lodged between the roller and its axis, or may hasten wear.
Potentially damaging dirt and debris may also enter the rail car via gaps formed along the attachment interface between the rail car roof and the top chord of the wall assemblies. This may tend to occur when a corrugated roof structure is used. While the peaks of the corrugation may abut the top chord along a longitudinal edge thereof, the valleys of the corrugation form passages for dirt and other debris to pass from the exterior to the interior of the rail car. This may occur even if the peaks abut an attachment plate or bracket of the top chord with the peaks abutting a generally flat surface of the plate or bracket instead of the edge of the top chord.
Typically, auto rack rail car doors, and in particular, radial arm doors, can be characterized as being thin shell structures. That is, the door has a developed span in the order of 5 ft to 9 ft wide, depending on the arc, a height on the order of 16 or 17 ft, and a skin thickness of perhaps 3/16″. Although the door obtains some stiffness from its arcuate shape, the large door area may be relatively vulnerable to damage, and may be prone to relatively large deflections. It is desirable for the shell to be stiff. Given the area of coverage of the door, even a relatively thin shell of steel sheet may have a considerable weight, particularly when fitted out with locks, rollers and other door hardware. Thus, it is undesirable to increase the general thickness of the door to obtain greater stiffness, since there is an inherent weight penalty.
In the past, attempts have been made to stiffen the door by providing welded angle irons, pipe, tubes and so on. However, it has been observed that welded reinforcements in doors may tend to be initiation sites for fatigue cracks, and even when repaired, may tend to crack again. It would be advantageous to provide reinforcements to give stiffness to the door, without necessarily relying on welds that might be prone to crack formation.
Another feature of auto rack doors relates to the portion of the door lying above the level of the wall top chord to enclose the gable end of the car. In earlier types of auto rack rail road car, such as that shown in Blunden Patent noted above, the radial arm door did not extend above the level of the top chord. However, this did not necessarily prevent determined thieves or vandals from climbing over the top of the door to obtain access to vehicles carried on the highest deck. Consequently, there have been several attempts to enclose the gable end. A disadvantage in many of these cases is the need to notch the door to accommodate the ladder support structure as noted above. Further, since the door tended not to be restrained at the roof line, the gable end portion of the door tended to be relatively weak. Thieves, or vandals, might be able to bend the upper portion of the door outward, and thereby gain access to the upper deck. It would be advantageous to discourage this activity by restraining a significant portion of the door to follow the arc of the roof line, and to lock the door to the roof when the door is in the closed position.